Disconnecting clamp



y 1955 R. s. TRACHTENBERG 3,183,469.

DISCONNECTING CLAMP Filed Dec. 51, 1962 INVENTOR.

ROBERT S. TEACHTENBEEG A TTORNEW United States Patent 3,183,459 DISCGNNECTING CLAMP Robert S. Trachtenberg, Stamford, Conn., assignor to Burndy Corporation, a corporation of New York Filed Dec. 31, 1962, Ser. No. 248,615 4 Claims. (Cl. 339-45) This invention relates generally to clamp type electrical connectors, and more particularly, to clamp connectors adapted to be separated from a transversely clamped object by an axial pull.

In loading and unloading gasoline and similar volatile, combustible substances on freight cars, tank trucks and the like, it is generally desirable to provide a temporary electrical connection between the vehicle body and earth potential to reduce the possibility of fire or explosion due to sparks caused by static electrical discharges. It is common practice to provide, for this purpose, a clamp type connector including a pair of spring loaded jaws having a contact making surface, and a pair of lever handles which may be compressed together to spread the jaws for receiving and releasing objects within them. The clamp is generally applied to any convenient conductive projection on the vehicle body. An electrical conductor securely connected to the contact surface of the jaws at one end, and to a source of earth potential at the other end, completes the required electrical connection.

Connections thus conveniently made are frequently thereafter forgotten, and the loaded or unloaded vehicle subsequently rolls away without further attention to the connector clamp. As a result, the entire cormector assembly, and possibly a substantial length of the connecting conductor, often accompany the departing vehicle on an unintended trip of unknown duration and uncertain destination.

Several methods of assuring the retention of these connector clamps at terminal stations have been employed at various times. Basic to most of these has been the provision of a strong chain to securely anchor the clamp to a fixed point, to force its separation from a moving vehicle. Since the jaws are generally stifliy spring loaded to provided adequate contact pressure, and the contact surface is usually sharpened to assure penetration of the coating of insulating grime characteristic of rolling transport stock, this method of forcible separation is not, alone, eminently satisfactory; it requires overly strong and expensive anchor chain to break the grip of the sharpened contact and frequently destroys or at least accelerates the wear of the contact surface.

A known improvement over the simple anchor chain involves the provision of a short length of transverse chain connected at each end to one of the uncompressed handles and having an axially extending anchor chain connected thereto intermediate the handles. The short chain then acts as a linkage for applying a transverse compression force to the handles in response to an axial pull on the anchor chain. Compression of the handles thus relieves the gripping pressure of the jaws as they are being axially separated from a clamped object. The transverse compression force transmitted to the handles by this method however, is seen to decrease substantially as the handles approach each other; accordingly in situations in which the handles are initially compressed to a significant extent as a result of the jaws being clamped on a relatively large object, the separation operation of this clamp releasing means is seriously impaired and contact damage during axial separation continues to be a problem.

It is therefore a principal object of this invention to provide an improved pressure relieving and disconnect means for a clamp connector, which operates independently of the initial position of the clamp jaws and releasing handles.

Another object of the invention is the provision of a readily releasable clamp connector assembly having optimum contact pressure.

Still another object is the provision of a clamp connector incorporating the above objects, which may be simply and inexpensively fabricated.

These and other objects, features and advantages of this invention will be made more apparent by reference to the following specification, taken in conjunction with the following drawings, in which:

FIGURE 1 is a side view of a clamp connector assembly constructed in accordance with this invention;

FiGURE 2 is a top view of the clamp connector; and

FIGURE 3 is a partial transverse section view of an integral conductor clamp taken in the plane 3--3 of FIG- URE 1.

Referring now more specifically to the drawings, the connector clamp 10 shown in FIGURE 1 may be seen to comprise generally a pair of clamping jaws 16, 18 and a pair of integrally attached operating handles 12, 14, all of which are pivotally attached about a pin axis 20, which may be a rivet having a head 22; a resilient spring 24 in the general shape of a double ended hair-pin acts about the pin axis to bias the jaws 16 and 18 together, and the handles 12 and 14 apart.

Each jaw terminates in a head portion which is provided with a threaded aperture 28 for receiving a threaded contact rod 29 having pointed contact surface 26. The threaded contacting rods permit minor adjustments in contact pressure to be made by advancing or withdrawing the points 26 relative to the arms 16, 18, and to each other. In addition, they facilitate replacement of the contacts. A lock nut 30 is provided to maintain the selected position of each contact rod.

In use, the handle 12 and 14 are grasped to the right of hand stops 13, which may be integrally formed, and are compressed together to spread the jaws 16, 13 and permit insertion or removal of an object between the contact surfaces 26.

A flexible cable such as 60, which may be a rope or metallic cable or synthetic fiber cord, having a force transmitting means 76 coupled thereto for applying an axial force A from a hook or cable which is in turn coupled to any convenient force producing means (not shown), is provided to compress the handles together in response to the force A, independently of an operators grasp.

The force direction changing loop 60 is captured to one handle within a tubular or ring shaped portion 44 which may be integrally formed, and to the other handle, which may be channel shaped by means of a pin or rod 46 inserted through opposed holes in the side Walls of the channel. An axial force A, applied in the axial direction shown by the arrow in FIGURE 1 when the surfaces 26 are clamped to a relatively stationary object, will produce a tensile force within the cable which will be transmitted transversely between cable engaging ring 44 and engaging pin 46 by the transversely extending cable portion 47. Thus, the full cable tension will always be applied substantially transversely between them, to supply full compressing force regardless of their initial or final relative position.

It should be noted that substantially equally eflicient cable-pulley operation might be achieved by fastening one end of a length of cable to one handle at ring 44, for example, extending the other end in slidable engagement around a pin 46, and then applying an axial force to that end, to in effect pull the pin 46 toward the cable engaging point 44 in response to an axial force.

It should similarly be noted that the ring 44 and pin 46 are only one possible combination of cable engaging means, and that either one may be fully substituted for Fatented May 11, 1965 aneaeee the other, or other slidable means, such as a pulley wheel,

may be substituted entirely.

The cable force transmitting means 76 includes a malleable tube portion 72 which may be secured to the ends of a cable inserted therein by indenting the tube as at. The tube is provided with an '74 in a known manner. apertured tab 75 which may be directly engaged by a force applying means (not shown). However, in the embodiment illustrated, the .tab is secured by means of a bolt 76 to a conductor grip or clamp 78, which wraps around an electrical cable such as 40 and grips it tightly as bolt 76 is tightened, to fix the position of the conductor relative to the clamp and relieve stress on the contact clamp-conductor connection described below. The grip 78 may then include an ear or tab 79 having an aperture 81, substantially axially aligned with the cable securing tube portion 72, for receiving a force applying means represented generally by the partial loop or hook 80, in FIGURE 2.

The insulated electrical cable 40, having a central conductor 42, provides the necessary electrical path from contact surfaces 26 to a source of earth potential (not shown). In this embodiment the entire body of clamp 18 is formed of conductive metal, which serves in part as an electrical path between the conductive contact rods 28 and conductor 42. The conductor is electrically and mechanically secured to the clamp 10 by means of an integrally formed conductor clamp 58 illustrated in detail in FIGURE 3. The clamp 50 comprises an integrally formed tab 57 on handle 14, which is provided with an opening 56 for receiving a mating projection 54 on a pressure plate 52. A bolt 58 passes through the plate 52 and engages a threaded aperture 59 in handle 14. The plate pivots about the projection 54' within opening 56 to clamp the conductor against the inner surface of the handle as bolt 58 is tightened. A lock washer 59 may be provided to secure the bolt in tightened position. The handle 14 may be further provided with an additional ring, or tube shaped portion 15, to act as a guide for positioning the cable 46 as the conductor 42 is inserted beneath the clamp plate 52.

The invention has thus been described but it is desired to be understood that it is not confined to the particular forms or usages shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit or the invention; therefore, the right is broadly claimed to employ all equivalent instrumentalities coming within the scope of the appendent claims, and by means Of'WhiCh objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of.

the many that can be employed to obtain these objects and accomplish these results.

I claim:

1. A tensile force disconnect clamp assembly, comprising: a clamp having a pair of opposed movable jaws adapted to be transversely compressed against an object axially inserted therebetween, a pair of handles connected to said jaws and adapted to be transversely compressed together to separate said jaws, and resilient means normally biasing said jaws together; and tensile force direction changing means for transmitting av given axial tensile force to said clamp handles both transversely and axially to respectively compress said handles and axially withdraw said clamp ,from an object inserted between said jaws; said force direction changing means including an elongate flexible cable having a substantially closed loop portion, first cable engaging means on one of said handles including an integral tubular portion opened at both ends for guiding a conductor and slidably engaging saidcable loop portion, means on said cablefor transmitting a given axial. force thereto, and second cable engaging means on the other of said handles for slidably engaging said cable within said loop; and means on said one of said handles for electrically and mechanically securing a conductor thereto.

2. The disconnect clamp assembly of claim 1 wherein said force transmitting means on said cable includes a cable gripping means having a malleable metal tube portion adapted to be mechanically secured by indenting to the ends of the cable inserted therein, and means on said tube for engaging a force applying means.

3. The disconnect clamp assembly of claim 2 wherein said force transmitting means further includes conductor gripping means for fixedly positioning said conductor relative to said transmitting means.

4. The disconnect clamp assembly of claim 1 wherein at least the said other of said handles is in'the form of a. U-shaped channel member having substantially parallel spaced apart side walls, and said second cable engaging means comprises a rod member extending between said sidewalls and secured thereto.

References Citedhy the Examiner UNITED STATES PATENTS 337,358 3/86 Allinson 2941 11 2,158,385 5/39 Schwien 339-45 X 2,644,142 6/53 Danberg.

2,781,224 2/57 Meloy 294-111 X 3,008,115 11/61 Oakes Q. 33945 3,049,690 8/62 Sparber 339,-45

JOSEPH D. SEERS, Primary Examiner. 

1. A TENSILE FORCE DISCONNECT CLAMP ASSEMBLY, COMPRISING: A CLAMP HAVING A PAIR OF OPPOSED MOVABLE JAWS ADAPTED TO BE TRANSVERSELY COMPRESSED AGAINST AN OBJECT AXIALLY INSERTED THEREBETWEEN, A PAIR OF HANDLES CONNECTED TO SAID JAWS AND ADAPTED TO BE TRANSVERSELY COMPRESSED TOGETHER TO SEPARATE SAID JAWS, AND RESILIENT MEANS NORMALLY BIASING SAID JAWS TOGETHER; AND TENSILE FORCE DIRECTIN CHANGING MEANS FOR TRANSMITTING A GIVEN AXIAL TENSILE FORCE TO SAID CLAMP HANDLES BOTH TRANSVERSELY AND AXIALLY TO RESPECTIVELY COMPRESS SAID HANDLES AND AXIALLY WITHDRAW SAID CLAMP FROM AN OBJECT INSERTED BETWEEN SAID JAWS; SAID FORCE DIRECTION CHANGNG MEANS INCLUDING AN ELONGATE FLEXIBLE CABLE HAVING A SUBSTANTIALLY CLOSED LOOP PORTION, FIRST CABLE ENGAGING MEANS ON ONE OF SAID HANDLES INCLUDING A INTEGRAL TUBULAR PORTION OPENED AT BOTH ENDS FOR GUIDING A CONDUCTOR AND SLIDABLY ENGAGING SAID CABLE LOOP PORTION, MEANS ON SAID CABLE FOR TRANSMITTING A GIVEN AXIAL FORCE THERETO, AND SECOND CABLE ENGAGING MEANS ON THE OTHER OF SAID HANDLES FOR SLIDABLY ENGAGING SAID CABLE WITHIN SAID LOOP; AND MEANS ON SAID ONE OF SAID HANDLES FOR ELECTRICALLY AND MECHANICALLY SECURING A CONDUCTOR THERETO. 